The Legionella testing service is a complex and specialized series of tests that are performed by specially training laboratory technicians. Our accredited method requires rigorous tests designed to isolate any potential presence of Legionella bacteria, and then to further determine the presence of the pathogen Legionella pneumophilia. Unlike our standard water tests, which take 2 – 3 days to complete. The testing of Legionella bacteria takes 7 – 10 days.
The international standard used to test for the detection and enumeration of Legionella species is ISO 11731 (SANS 11731). This method is useful for a variety of environmental samples including potable, industrial, and natural waters as well as associated materials such as deposits, sediments, and slime.
Sampling is conducted by trained technical consultants, in sterile polyethylene sampling bags. Samples are transported under 10°C, protected from heat and sunlight in cooler boxes.
The bacteria in the water sample can be concentrated by centrifugation. The sample is shaken to resuspend any deposit that may have settled. It is then dispensed into sterile screw-capped conical bottom bottles and centrifuged for 30 minutes at 3000 g. The supernatant is removed aseptically and discarded. The deposit is then resuspended in a specified volume of diluent, this concentrate is now referred to as the prepared sample.
The prepared sample is then divided into three portions, one is used without any further treatment and the other two portions are subjected to acid treatment and heat treatment.
The prepared sample is pipetted onto specialized agar plates and incubated for up to ten days. The plates are observed at least three times at intervals of 2 to 4 days during the ten-day incubation period. A ten-day incubation period is recommended as Legionella are slow-growing and may be masked by the growth of other bacteria.
Colonies are further confirmed according to serogroup-1, serogroup 2-14, or Legionella spp., using a latex test kit.